Intensified hybrid solid-state sensor

ABSTRACT

An intensified solid-state imaging sensor includes a photo cathode for converting light from an image into electrons, an electron multiplying device for receiving electrons from the photo cathode, and a solid-state image sensor including a plurality of pixels for receiving the electrons from the electron multiplying device through a plurality of channels of the electron multiplying device. The solid-state image sensor generates an intensified image signal from the electrons received from the electron multiplying device. The plurality of channels are arranged in a plurality of channel patterns, and the plurality of pixels are arranged in a plurality of pixel patterns. Each of the plurality of channel patterns is mapped to a respective one of the plurality of pixel patterns such that electron signals from each of the plurality of channel patterns is substantially received by the single respective one of the plurality of pixel patterns.

RELATED APPLICATION

The present application is a continuation-in-part of pending U.S. patentapplication Ser. No. 09/973,907 filed on behalf of inventors Rudolph G.Benz, Nils I. Thomas, and Arlynn W. Smith on Oct. 9, 2001, now U.S. Pat.No. 6,747,258, titled INTENSIFIED HYBRID SOLID-STATE SENSOR WITH ANINSULATING LAYER, assigned to the assignee of the present application,and incorporated in this application by reference.

FIELD OF THE INVENTION

The present invention is directed to an intensified hybrid solid-statesensor. More particularly, the present invention relates to an imageintensifier using a CMOS or CCD sensing device connected in closephysical proximity to a microchannel plate (MCP) and photo cathode.

BACKGROUND OF THE INVENTION

The present invention relates to the field of image intensifying devicesusing solid-state sensors, such as a CMOS or CCD device. Imageintensifier devices are used to amplify low intensity light or convertnon-visible light into readily viewable images. Image intensifierdevices are particularly useful for providing images from infrared lightand have many industrial and military applications. For example, imageintensifier tubes are used for enhancing the night vision of aviators,for photographing astronomical bodies and for providing night vision tosufferers of retinitis pigmentosa (night blindness).

There are three types of known image intensifying devices in prior art;image intensifier tubes for cameras, all solid-state CMOS and CCDsensors, and hybrid EBCCD/CMOS (Electronic Bombarded CCD or CMOSsensor).

Image intensifier tubes are well known and used throughout manyindustries. Referring to FIG. 1, a current state of the prior artGeneration III (GEN III) image intensifier tube 10 is shown. Examples ofthe use of such a GEN III image intensifier tube in the prior art areexemplified in U.S. Pat. No. 5,029,963 to Naselli, et al., entitledREPLACEMENT DEVICE FOR A DRIVER'S VIEWER and U.S. Pat. No. 5,084,780 toPhillips, entitled TELESCOPIC SIGHT FOR DAYLIGHT VIEWING. The GEN IIIimage intensifier tube 10 shown, and in both cited references, is of thetype currently manufactured by ITT Corporation, the assignee herein. Inthe intensifier tube 10 shown in FIG. 1, infrared energy impinges upon aphoto cathode 12. The photo cathode 12 is comprised of a glass faceplate14 coated on one side with an antireflection layer 16, a galliumaluminum arsenide (GaAIAs) window layer 17 and a gallium arsenide (GaAs)active layer 18. Infrared energy is absorbed in GaAs active layer 18thereby resulting in the generation of electron/hole pairs. The producedelectrons are then emitted into the vacuum housing 22 through a negativeelectron affinity (NEA) coating 20 present on the GaAs active layer 18.

A microchannel plate (MCP) 24 is positioned within the vacuum housing22, adjacent the NEA coating 20 of the photo cathode 12. Conventionally,the MCP 24 is made of glass having a conductive input surface 26 and aconductive output surface 28. Once electrons exit the photo cathode 12,the electrons are accelerated toward the input surface 26 of the MCP 24by a difference in potential between the input surface 26 and the photocathode 12 of approximately 300 to 900 volts. As the electrons bombardthe input surface 26 of the MCP 24, secondary electrons are generatedwithin the MCP 24. The MCP 24 may generate several hundred electrons foreach electron entering the input surface 26. The MCP 24 is subjected toa difference in potential between the input surface 26 and the outputsurface 28, which is typically about 1100 volts, whereby the potentialdifference enables electron multiplication.

As the multiplied electrons exit the MCP 24, the electrons areaccelerated through the vacuum housing 22 toward the phosphor screen 30by the difference in potential between the phosphor screen 30 and theoutput surface 28 of approximately 4200 volts. As the electrons impingeupon the phosphor screen 30, many photons are produced per electron. Thephotons create the output image for the image intensifier tube 10 on theoutput surface 28 of the optical inverter element 31.

Image intensifiers such as those illustrated in FIG. 1 have advantagesover other forms of image intensifiers. First, intensifiers have alogarithmic gain curve. That is, the gain decreases as the input lightlevel is increased. This matches the human eye response particularlywhen bright lights are in the same scene as low lights. Most solid-statedevices have a linear response; i.e., the brighter the light thebrighter the output signal. The result is that bright lights appear muchbrighter to a viewer of a solid-state system and tend to wash out thescene. Solid-state sensors can be modified to produce a gain decrease asinput light is increased, however, this requires changing the amplifiergain, using shuttering, or using anti-blooming control.

Another advantage of image intensifiers is the ability to function overa large range of input light levels. The power supply can control thecathode voltage and thereby change the tube gain to fit the scene. Thustubes can function from overcast starlight to daytime conditions.

However, image intensifier/I² cameras suffer from numerousdisadvantages. The electron optics of the phosphor screen produces a lowcontrast image. This results in the object looking fuzzier to the humanobserver, or solid-state sensor, when viewed through an imageintensifier. Although this deficiency has been somewhat reduced withfurther image intensifier development, solid-state imagers generallyhave better performance.

Another disadvantage with image intensifier/I² cameras is “halo.” Haloresults from electrons being reflected off either the MCP or the screen.The reflected electrons are then amplified and converted into light inthe form of a ring around the original image. In image tubes, the halofrom electrons reflected from the MCP has been reduced to a negligibleeffect for the most recent production tubes. However, the halo from thescreen section still exists, although not to the degree of the cathodehalo. Nevertheless, the screen halo is still a significant defect inimaging systems when a CCD or CMOS array is coupled to the imageintensifier. This is because these arrays are more sensitive than theeye to the low light levels in the screen halo.

Another disadvantage is that image intensifiers do not have a method ofproviding electronic read-out. Electronic read-out is desired so thatimagery from thermal sensors may be combined with intensified imagerywith the result that the information from both spectra will be viewed atthe same time. One solution has been to create an I² camera by couplinga CCD or CMOS array to an image intensifier tube. When a solid-statedevice is coupled to an image tube the resultant camera has allperformance defects of the image tube that is low contrast, often poorlimiting resolution due to coupling inefficiencies and the added cost ofthe image tube to the camera.

Solid-state devices typically include CCD or CMOS. They function bydirectly detecting the light, electronically transferring the signal tosolid-state amplifiers, then displaying the image on either a televisiontype tube or display such as a liquid crystal display. FIGS. 2 a and 2 billustrate a flow chart and schematic diagram for a typical CCD sensor.

CCD and CMOS sensors are solid-state devices; that is, there is novacuum envelope and the output is an electronic signal that must bedisplayed elsewhere and not within the sensor. The solid-state devicesoperate with power of 5–15 volts. The light is detected in individualpixels as labeled “s” and translated into electrons that are stored inthe pixel until the pixel is read out to the storage register. From thestorage register the electronic information contained in multiple pixelsis then transferred to a read out register and then to output amplifiersand then to a video display device such as a cathode ray tube.

The disadvantages of an all solid-state device are poor low light levelperformance, potential blooming from bright light sources, poor limitingresolution, and high power consumption. The poor low light performanceis due to dark current and read-out noise resulting in low signal-noiseratios. If a signal gain mechanism were provided prior to read-out thisissue would be negated, as sufficient signal would exist to overcome thenoise sources. Solid-state device architectures usually do not permit anamplification section prior to read-out. The poor limiting resolution isdue to large pixel sizes usually chosen in an attempt to collect a largesignal and thereby increase the signal to noise ratio. Thesedisadvantages have effectively prevented the use of solid-state sensorsin night vision applications. The advantages of solid-state devices arebetter image contrast as compared to the image intensifier/I² camera,the availability of electronic read-out, and lower cost, particularlywhen the solid-state sensor is a CMOS array.

As can be seen, the strengths and weaknesses of image intensifiers andsolid-state sensors compliment each other and theoretically acombination of both devices would give better performance. One suchcombination proposed as an alternative to image intensifiers/I² camerasand solid-state sensors, is the electron bombarded CCD/CMOS sensor(EBCCD/CMOS). This device consists of the photo-cathode and bodyenvelope of the image tube, and either a CCD or CMOS sensor integratedinto this envelope. An illustrative example of an EBCCD/CMOS sensor isshown in FIG. 3. A high voltage is applied between the cathode andsolid-state sensor so that the resulting electrons are amplified withinthe silicon in the solid-state sensor by electron bombardment.

The advantages of the EBCCD/CMOS device are that it provides electronicread-out. But the disadvantages are numerous. First, the intra-scenedynamic range is compressed. This means that overall contrast within thescene, when bright objects are next to dark objects, is reduced comparedto an image intensifier/I² camera and all solid-state device. Secondly,the sensor suffers “halo” degradation of the image around bright lightsdue to electrons reflected off of the solid-state sensor. This haloexists in regular image tubes; however, technological improvements havereduced the halo to the point of non-existence. Thirdly, the very highvoltage required to operate the device (2–10 kV) damages the siliconsurface causing decay in performance over time.

Therefore, it is an object of the present invention to provide anintensified hybrid solid-state sensor that combines the functions of theimage intensifier, good signal-to-noise ratio and high logarithmic gain,with the electronic read-out functions either of a Complementary MetalOxide Semiconductor (CMOS) or Charged Coupled Device (CCD).

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention, anintensified solid-state imaging sensor includes a photo cathode forconverting light from an image into electrons. The intensifiedsolid-state imaging sensor also includes an electron multiplying devicefor receiving electrons from the photo cathode. The electron multiplyingdevice outputs a greater number of electrons than the electronmultiplying device receives from the photo cathode. The intensifiedsolid-state imaging sensor also includes a solid-state image sensorincluding a plurality of pixels for receiving the electrons from theelectron multiplying device through a plurality of channels of theelectron multiplying device. The solid-state image sensor generates anintensified image signal from the electrons received from the electronmultiplying device. The plurality of channels are arranged in aplurality of channel patterns, and the plurality of pixels are arrangedin a plurality of pixel patterns. Each of the plurality of channelpatterns is mapped to a respective one of the plurality of pixelpatterns such that electron signals from each of the plurality ofchannel patterns is substantially received by the single respective oneof the plurality of pixel patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention will become more clearly understood it willbe disclosed in greater detail with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic illustration of a typical image intensifying tube;

FIG. 2A is a flow chart for a typical CCD sensor;

FIG. 2B is a schematic diagram of a typical CCD imaging surface;

FIG. 3 is a cross-sectional view of a typical Electron Bombarded CCDdevice;

FIG. 4A is a cross-sectional view of an intensified hybrid solid-statesensor according to the present invention;

FIG. 4B is a schematic representation of an intensified hybridsolid-state sensor according to the present invention;

FIG. 5A is a schematic illustration of a microchannel plate (MCP) and aback thinned CCD for use in the present invention;

FIG. 5B is a schematic illustration of a microchannel plate (MCP) and astandard CCD for use in the present invention;

FIG. 5C is a perspective view of a CMOS-type image sensor for use withthe present invention;

FIG. 6A is a perspective view of MCP channels having round profiles anda CMOS well;

FIG. 6B is a perspective view of MCP channels having square profiles anda CMOS well;

FIG. 7A is a schematic top view of a large pixel/small MCP channel pitchper unit area of the sensor surface according to the present invention;

FIG. 7B is a schematic top view of a one-to-one pixel to MCP channel perunit area of the sensor surface according to the present invention;

FIG. 7C is a schematic top view of a small CMOS pixel pitch/large MCPchannel per unit area of the sensor surface according to the invention;

FIG. 8 is an illustration of misalignment of an electron multiplyingdevice channel pattern with an image sensor pixel pattern for use indescribing the benefits of exemplary embodiments of the presentinvention;

FIG. 9A is a block diagram illustration of an aligned electronmultiplying device channel pattern with an image sensor pixel patternaccording to an exemplary embodiment of the present invention;

FIG. 9B is a block diagram illustration of another aligned electronmultiplying device channel pattern with an image sensor pixel patternaccording to another exemplary embodiment of the present invention;

FIG. 9C is a block diagram illustration of yet another aligned electronmultiplying device channel pattern with an image sensor pixel patternaccording to another exemplary embodiment of the present invention;

FIG. 9D is a block diagram illustration of yet another aligned electronmultiplying device channel pattern with an image sensor pixel patternaccording to another exemplary embodiment of the present invention; and

FIG. 9E is a block diagram illustration of yet another aligned electronmultiplying device channel pattern with an image sensor pixel patternaccording to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred features of embodiments of this invention will now bedescribed with reference to the figures. It will be appreciated that thespirit and scope of the invention is not limited to the embodimentsselected for illustration. Also, it should be noted that the drawingsare not rendered to any particular scale or proportion. It iscontemplated that any of the configurations and materials describedhereafter can be modified within the scope of this invention.

In copending U.S. patent application Ser. No. 09/973,907, the presentinvention was described as providing an intensified hybrid solid-statesensor. The solid-state sensor, according to the present invention,includes an imaging device comprising a solid-state sensor assembledwith an image intensifier cathode, microchannel plate (MCP), and bodyenvelope. This device combines the best functions of the imageintensifier, good signal-to-noise ratio and high logarithmic gain, withthe electronic read-out functions either of a Complementary Metal OxideSemiconductor (CMOS) or Charged Coupled Device (CCD). Applications forthis invention are primarily night vision systems where good low lightsensitivity and high gain are required.

FIG. 4B is a schematic representation of an intensified hybridsolid-state sensor device 41 according to the present invention. Sensor41 comprises a standard image tube photo cathode 54, a microchannelplate (MCP) 53 and a solid-state imaging sensor 56. Solid-state imagingsensor 56 can be any type of solid-state imaging sensor. Preferably,solid-state imaging sensor 56 is a CCD device. More preferably,solid-state imaging sensor 56 is a CMOS imaging sensor. FIG. 5Aillustrates a back-thinned CCD imaging device as imaging sensor 56′. Inthis embodiment, MCP 53 is connected with a back-thinned CCD sensor 56′.Back-thinned CCD 56′ includes an electron receiving surface, such asdiffusion collection area 56 a′ and a readout area 62. FIG. 5Billustrates an alternative standard CCD imaging device including MCP 53connected to a standard CCD 56″. CCD 56″ includes an oxide cover 63 andplurality of collection wells 64. FIG. 5C illustrates the sensor as aCMOS sensor, including a CMOS substrate 56″ and a plurality ofcollection wells 65.

For various reasons, CCD based image sensors are limited or impracticalfor use in many applications. First, CCDs require at least twopolysilicon layers with a buried-channel implant to achieve their highperformance, meaning that they cannot be fabricated using standard CMOSfabrication processes. Second, the level of integration that can beachieved with CCD based imagers is low since they cannot include thedevices necessary to integrate them with other devices in anapplication. Finally, the circuits used to transfer data out of theimage array to other devices on the system board, such as Digital SignalProcessors (DSPs) and other image processing circuits, have a largecapacitance and require voltages higher than the other circuits. Sincethe currents associated with charging and discharging these capacitorsare usually significant, a CCD imager is not particularly well suitedfor portable or battery operated applications.

As such, less expensive image sensors fabricated out of integratedcircuits using standard CMOS processes are desirable. Essentially, witha CMOS type imager sensor, a photo diode, phototransistor or othersimilar device is employed as a light-detecting element. The output ofthe light-detecting element is an analog signal whose magnitude isapproximately proportional to the amount of light received by theelement. CMOS imagers are preferred in some applications since they useless power, have lower fabrication costs and offer higher systemintegration compared to imagers made with CCD processes. Moreover, CMOSimagers have the added advantages that they can be manufactured usingprocesses similar to those commonly used to manufacture logictransistors. While the preferred embodiment of the inventionincorporates a CMOS sensor as the imaging sensor 56, any solid-stateimaging sensor would work and is within the scope of the presentapplication.

Referring again to FIG. 4B, photo cathode 54 can be a standard photocathode as used in any known type of image intensifying device. Photocathode 54 can be, but is not limited to, a material such a GaAs,Bialkali, InGaAs, and the like. Photo cathode 54 includes an input side54 a and an output side 54 b. MCP 53 can be, but is not limited to asilicon or glass material, and is preferably about 10 to 25 mm thick.MCP 53 has a plurality of channels 52 formed between an input surface 49and output surface 50. Channels 52 can have any type of profile, forexample a round profile 52′ (FIG. 6A) or a square profile 52″ (FIG. 6B.)MCP 53 is connected to electron receiving surface 56 a of imaging sensor56.

Preferably, output surface 50 of MCP 53 is physically in contact withelectron receiving surface 56 a of imaging sensor 56. However,insulation may be necessary between MCP 53 and imaging sensor 56.Accordingly, a thin insulating spacer 55 may be inserted between outputsurface 50 of MCP 53 and electron receiving surface 56 a of imagingsensor 56. Insulating space 55 can be made of any electrical insulatingmaterial and is preferably formed as a thin layer, no more than severalmicrons thick, deposited over electron receiving surface 56 a of imagingsensor 56. For example, such an insulating spacer may be, but is notlimited to, an approximately 10 μm thick film. Alternatively, insulatingspacer 55 could be a film formed on the output surface 50 of MCP 53 (notshown).

CMOS imaging sensor 56 includes electron receiving surface 56 a andoutput 56 b. The increased number of electrons 47 emitted from MCP 53strike electron receiving surface 56 a. Electron receiving surface 56 acomprises a CMOS substrate 56′″ and a plurality of collection wells 65(FIG. 5C). Electrons 47 (See FIG. 4B) collected in collection wells 65are processed using standard signal processing equipment for CMOSsensors to produce an intensified image signal that is sent throughoutput 56 b to an image display device 46.

An electric biasing circuit 44 provides a biasing current to sensor 41.Electric biasing circuit 44 includes a first electrical connection 42and a second electrical connection 43. First electrical connection 42provides a biasing voltage between photo cathode 54 and MCP 53. Thebiasing voltage from first electrical connection 42 is preferably set soas to be less than the biasing voltage than the EBCCD/CMOS sensorcathode to CCD voltage, i.e., 2–10 kV. For example, one preferredbiasing voltage could be similar to that of image tubes, such as ˜1400V.Second electrical connection 43 applies a biasing voltage of between MCP53 and CMOS sensor 56. Preferably, the biasing voltage applied throughsecond electrical connection 43 is significantly less than the imagetube—screen voltage of about 4200V of the prior art devices (FIG. 1).For example, the biasing voltage applied through second electricalconnection 43 could be, but is not limited to ˜100V. FIG. 4A illustratesone potential configuration of the sensor 41. In this configuration,photo cathode 54, MCP 53, and imaging sensor 56 are maintained in avacuum body or envelope 61 as a single unit, in close physical proximityto each other.

Referring to FIG. 4B, in operation, light 58, 59 from an image 57 entersintensified hybrid solid-state sensor 41 through input side 54 a ofphoto cathode 54. Photo cathode 54 changes the entering light intoelectrons 48, which are output from output side 54 b of photo cathode54. Electrons 48 exiting photo cathode 54 enter channels 52 throughinput surface 49 of MCP 53. After electrons 48 bombard input surface 49of MCP 53, secondary electrons are generated within the plurality ofchannels 52 of MCP 53. MCP 53 may generate several hundred electrons ineach of channels 52 for each electron entering through input surface 49.Thus, the number of electrons 47 exiting channels 52 is significantlygreater than the number of electrons 48 that entered channels 52. Theintensified number of electrons 47 exit channels 52 through output side50 of MCP 53, and strike electron receiving surface 56 a of CMOS imagingdevice 56.

FIGS. 6A–6B illustrate how the increased number of electrons 47 exitchannels 52 (i.e., channels 52′ in FIG. 6A, channels 52″ in FIG. 6B) andstrike a particular collection well 65′ of CMOS imaging sensor 56. Ascan be seen from these illustrations, a relationship exists between thecollection wells 65′ and the number of channels 52 which emit electrons47. In general, adjacent channels 52 of MCP 53 are separated by apredetermined channel pitch 52 a. FIGS. 6A–6B illustrate a channel pitch52 a that results in more than one channel 52 per collection well 65′.

FIGS. 7A–7C illustrate three different alternatives of CMOS well/channelpitch relationships according to the invention. FIG. 7A illustrates onerelationship between channel pitch 52 and a CMOS well 65′. In this case,channel pitch 52 is relatively small, while the size of CMOS well 65′ isrelatively large. This permits several electrons 47 from two or morechannels 52 to strike CMOS collection well 65′. FIG. 7B illustratesanother CMOS well/channel pitch relationship. In this embodiment,channel pitch 52 and the size of CMOS collection well 65′ areapproximately in a one-to-one relationship. As such electrons 47′ from asingle channel 52 strike a single collection well 65′. FIG. 7Cillustrates another CMOS well/channel pitch relationship where channelpitch 52 is relatively large and the size of CMOS collection well 65′ isrelatively small. In this case electrons 47″ from a single channel 52strike multiple collection wells 65′. While each of these structuresprovide various advantages, the relationship illustrated in FIG. 7A ispreferred for the present invention.

As a result, the intensified hybrid solid-state sensor operates indifferent conditions than any of the other prior art concepts. Theresult is that the MCP 53 can be mounted directly on the CMOS sensor 56giving the hybrid device similar contrast to the all solid-state device,but with low halo, good signal-to-noise ratio, and logarithmic gain ofthe image tube. Since operating voltages are lower, the hybrid devicecan be gated like an image intensifier allowing operation from overcaststarlight condition to daytime operation. The hybrid sensor has betterhalo from the lack of physical gap between MCP 53 and CMOS sensor 56.This lack of physical separation in the two components is also whycontrast is improved when compared to the EBCCD/CMOS or imageintensified camera. The hybrid device also has the logarithmic gaincurve of the image tube. Unlike the EBCCD/CMOS sensor, the hybrid sensorcan be gated due to the low cathode voltages.

Many of the components in image intensifier tubes relate to samplingdevices. Such sampling devices collect a discrete spatial sample of aninput signal and provide a discrete sampled output signal. Examples ofsuch sampling devices in image intensifier tubes are the microchannelplate and the fiber-optic screen. For example, an MCP collects inputelectrons in the pores/channels, and outputs electrons from those verysame pores/channels. In the case of a fiber-optic device, eachindividual fiber collects a spatial sample of light, therebyconstraining the light within a fiber, and projecting the sampled imageat the output of the fiber.

When such spatially sampled signals are overlayed on each other severalpatterns can be observed at the output. FIG. 8 illustrates aconfiguration 800 relating to pixels of a solid-state image sensoroverlayed with channels of an electron multiplying device. Morespecifically, configuration 800 illustrates pixels 802 a, 802 b, 802 c,and 802 d of a solid-state image sensor overlayed with channels 804 a,804 b, 804 c, 804 d, 804 e, 804 f, and 804 g of an electron multiplyingdevice. Configuration 800 illustrates misalignment of the samplingbetween the solid-state image sensor and the electron multiplyingdevice. More specifically, some portions of channels 804 a, 804 b, 804c, 804 d, 804 e, 804 f, and 804 g align with pixels 802 a, 802 b, 802 c,and 802 d ; however, other portions of channels 804 a, 804 b, 804 c, 804d, 804 e, 804 f, and 804 g do not align with pixels 802 a, 802 b, 802 c,and 802 d.

These misalignments, when viewed (e.g., by a person viewing a monitor),can show up as one of a number of undesirable electro-optical patterns.For example, such an electro-optical pattern is known as Moiré. Moiré(and other electro-optical patterns such as aliasing) tend to be verydistracting to a person trying to view real objects through suchmisaligned patterns.

Such optical patterns (i.e., misalignment patterns) often manifestthemselves when the optical transfer quality from one element to anotheris very good. For example, FIG. 8 illustrates such a high transferquality. In FIG. 8, if the edges of the pixels and/or channels were notquite so clear (i.e., the edges were fuzzy), the actual image beingviewed may not display the Moiré patterns. When the electron multiplyingdevice (e.g., the MCP) is laid in contact (or substantial contact) withthe solid-state image sensor (e.g., a CMOS imager), very high qualityimage transfer occurs between the channels of the electron multiplyingdevice and the pixels of the solid state image sensor. In suchconfigurations, optical misalignment patterns such as Moiré would tendto be visible.

According to an exemplary embodiment of the present invention, Moiré andother undesirable optical patterns are avoided or substantially reducedby (1) arranging a plurality of channels of an electron multiplyingdevice in a plurality of channel patterns, (2) arranging a plurality ofpixels of a solid-state image sensor in a plurality of pixel patterns,and (3) mapping each of the plurality of channel patterns to arespective one of the plurality of pixel patterns such that electronsignals from each of the plurality of channel patterns is substantiallyreceived by the single respective one of the plurality of pixelpatterns. This alignment may be in any of a number of configurations, solong as the signals from each of the channel patterns is substantiallyaligned with the respective one of the pixel patterns such that opticalmisalignment (such as that illustrated in FIG. 8) does not occur.

According to another exemplary embodiment of the present invention, eachof the plurality of channel patterns may be rotationally andtranslationally aligned with the respective one of the plurality ofpixel patterns.

For example, FIG. 9A illustrates an exemplary mapping 900, where mapping900 includes pixels of a solid-state image sensor (arranged as 4 pixelpatterns, each of the pixel patterns including a single pixel) overlayedwith channels of an electron multiplying device (arranged as 4 channelpatterns, each of the channel patterns including a single channel)(because of the mapping/registration of the channel patterns to pixelpatterns in FIG. 9A, each of the mappings appears as a single square;however, each of the squares actually represents a pixel patternoverlayed with a channel pattern). More specifically, mapping 900illustrates pixels 902 a, 902 b, 902 c, and 902 d (each of whichrepresents a pixel pattern having a single pixel) of a solid-state imagesensor overlayed with channels 904 a, 904 b, 904 c, and 904 d (each ofwhich represents a channel pattern having a single channel). In thisembodiment a single one of channels 904 a, 904 b, 904 c, and 904 d isaligned/mapped with a corresponding one of pixels 902 a, 902 b, 902 c,and 902 d. Further, the channels (e.g., pores of an MCP) aresubstantially the same size as, and have substantially the samecenter-to-center spacing as, the pixels (e.g., pixels of an imagesensor).

In certain exemplary embodiments of the present invention, it isdesirable to align the channels of the electron multiplying device withthe pixels of the solid-state image sensor during assembly of theimaging sensor. One assembly method to ensure proper alignment is toshine a light through the electron multiplying device, thereby allowingfor observation of the reflected pattern of the solid-state imagesensor. If no undesirable misalignment pattern is visible (e.g., Moiré),then the channels of the electron multiplying device are substantiallyaligned with the pixels of the solid-state image sensor. Of course,other methods of alignment are available.

FIG. 9A is only one of a number of mapping configurations that providesfor alignment of the channel patterns of the electron multiplying devicewith the respective pixel patterns of the solid-state image sensor. Anumber of additional configurations are possible. FIGS. 9B–9E areadditional examples of such mapping configurations.

FIG. 9B illustrates an exemplary mapping 910, where mapping 910 includespixels of a solid-state image sensor (arranged as 4 pixel patterns, eachof the pixel patterns including a single pixel) overlayed with channelsof an electron multiplying device (arranged as 4 channel patterns, eachof the channel patterns including a single channel). More specifically,mapping 910 illustrates pixels 912 a, 912 b, 912 c, and 912 d of asolid-state image sensor (each of which represents a pixel patternhaving a single pixel) overlayed with channel patterns 914 a, 914 b, 914c, and 914 d (each of which represents a channel pattern having a singlechannel). In this embodiment a single one of channels 914 a, 914 b, 914c, and 914 d is aligned with a corresponding one of pixels 912 a, 912 b,912 c, and 912 d. The embodiment illustrated in FIG. 9B is similar tothe embodiment illustrated in FIG. 9A in that there is a one-to-onecorrelation between channels of the electron multiplying device and thepixels of the solid-state image sensor; however, the channels of theelectron multiplying device in FIG. 9B are not substantially the samesize and/or shape as the pixels of the solid-state image sensor.Regardless, the channels of the electron multiplying device and thepixels of the solid-state image sensor are aligned with one another.Because of the alignment, there is a substantial reduction in thepotential for undesirable optical patterns (e.g., Moiré).

FIG. 9C illustrates an exemplary mapping 920, where mapping 920 includespixels of a solid-state image sensor (arranged as 4 pixel patterns, eachof the pixel patterns including a single pixel) overlayed with channelsof an electron multiplying device (arranged as 4 channel patterns, eachof the channel patterns including four channels). More specifically,mapping 920 illustrates pixels 922 a, 922 b, 922 c, and 922 d of asolid-state image sensor (each of which represents a pixel patternhaving a single pixel) overlayed with channels 924 a, 924 b, 924 c, and924 d (four of which represent a single channel pattern). In thisembodiment a single one of pixels 922 a, 922 b, 922 c, and 922 d ismapped/aligned with a corresponding channel pattern, where each of thechannel patterns includes four channels (i.e., four of channels 924 a,924 b, 924 c, and 924 d, respectively). The mapping/alignment of thechannel patterns of the electron multiplying device and the pixelpatterns of the solid-state image sensor results in a substantialreduction in the potential for undesirable optical patterns (e.g.,Moiré).

FIG. 9D illustrates an exemplary mapping 930, where mapping 930 includespixels of a solid-state image sensor (arranged as 9 pixel patterns, eachof the pixel patterns including a single pixel) overlayed with channelsof an electron multiplying device (arranged as 9 channel patterns, eachof the channel patterns including a single channel). More specifically,mapping 930 illustrates pixels 932 a, 932 b, 932 c, 932 d, 932 e, 932 f,932 g, 932 h, and 932 i of a solid-state image sensor (each of whichrepresents a pixel pattern including a single pixel) overlayed withchannels 934 a, 934 b, 934 c, 934 d, 934 e, 934 f, 934 g, 934 h, and 934i (each of which represents a channel pattern having a single channel).In this embodiment a single one of channels 934 a, 934 b, 934 c, 934 d,934 e, 934 f, 934 g, 934 h, and 934 i is mapped/aligned with acorresponding one of pixels 932 a, 932 b, 932 c, 932 d, 932 e, 932 f,932 g, 932 h, and 932 i. The mapping/alignment of the channel patternsof the electron multiplying device and the pixel patterns of thesolid-state image sensor results in a substantial reduction in thepotential for undesirable optical patterns (e.g., Moiré).

FIG. 9E illustrates an exemplary mapping 940, where mapping 940 includespixels of a solid-state image sensor (arranged as 4 pixel patterns, eachof the pixel patterns including four pixels) overlayed with channels ofan electron multiplying device (arranged as 4 channel patterns, each ofthe channel patterns including a single channel). More specifically,mapping 940 illustrates pixels 942 a, 942 b, 942 c, and 942 d (four ofwhich represent a single pixel pattern) of a solid-state image sensoroverlayed with channels 944 a, 944 b, 944 c, and 944 d of an electronmultiplying device (each of which represents a channel pattern having asingle channel). In this embodiment a single one of channels 944 a, 944b, 944 c, and 944 d is mapped/aligned with a corresponding pixelpattern, where each of the pixel patterns includes four pixels (i.e.,four of wells 942 a, 942 b, 942 c, and 942 d, respectively). Themapping/alignment of the channel patterns of the electron multiplyingdevice and the pixel patterns of the solid-state image sensor results ina substantial reduction in the potential for undesirable opticalpatterns (e.g., Moiré).

The embodiments of the present invention illustrated in FIGS. 9A–9E, anddescribed above, are exemplary in nature. Various alternativeconfigurations are contemplated. For example, the number of channels ineach of the channel patterns, and/or the number of pixels in each of thepixel patterns may be varied in accordance with the present invention.Further, the size and/or shape of the channels and/or pixels may bevaried in accordance with the present invention. Further still, themapping of channel patterns to pixel patterns may also be varied inaccordance with the present invention.

As used herein, a pixel is intended to refer to an element of an imagesensor (e.g., a solid-state image sensor) that receives electrons orelectron energy. Pixels include wells for storing the electron energyreceived.

The above detailed description of a preferred embodiment of theinvention sets forth the best mode contemplated by the inventor forcarrying out the invention at the time of filing this application and isprovided by way of example and not as a limitation. Accordingly, variousmodifications and variations obvious to a person of ordinary skill inthe art to which it pertains are deemed to lie within the scope andspirit of the invention as set forth in the following claims.

1. An intensified solid-state imaging sensor comprising: a photo cathodefor converting light from an image into electrons; an electronmultiplying device for receiving electrons from the photo cathode, theelectron multiplying device outputting a greater number of electronsthan the electron multiplying device receives from the photo cathode;and a solid-state image sensor including a plurality of pixels forreceiving the electrons from the electron multiplying device through aplurality of channels of the electron multiplying device, thesolid-state image sensor generating an intensified image signal from theelectrons received from the electron multiplying device, the pluralityof channels being arranged in a plurality of channel patterns, and theplurality of pixels being arranged in a plurality of pixel patterns,each of the plurality of channel patterns being mapped to a respectiveone of the plurality of pixel patterns and each of the pixels and eachof the channels includes, respectively, a pixel face surface and achannel face surface in opposing relationship to each other, the pixeland channel face surfaces each having a linear boundary, whereinrespective linear boundaries of the plurality of channels are arrangedso that they do not cross respective linear boundaries of the pluralityof pixels.
 2. The intensified solid-state imaging sensor of claim 1wherein each of the plurality of channel patterns comprises a singlechannel, and each of the plurality of pixel patterns comprises a singlepixel.
 3. The intensified solid-state imaging sensor of claim 2 whereineach of the plurality of channel patterns is substantially the same sizeand shape as the respective one of the plurality of pixel patterns. 4.The intensified solid-state imaging sensor of claim 1 wherein each ofthe plurality of channel patterns comprises a plurality of channels, andeach of the plurality of pixel patterns comprises a single pixel.
 5. Theintensified solid-state imaging sensor of claim 1 wherein each of theplurality of channel patterns comprises a single channel, and each ofthe plurality of pixel patterns comprises a plurality of pixels.
 6. Theintensified solid-state imaging sensor of claim 1 wherein each of theplurality of channel patterns comprises a plurality of channels, andeach of the plurality of pixel patterns comprises a plurality of pixels.7. The intensified solid-state imaging sensor of claim 1 wherein each ofthe plurality of channel patterns is rotationally and translationallyaligned with the respective one of the plurality of pixel patterns. 8.The intensified solid-state imaging sensor of claim 1 wherein theelectron multiplying device comprises a multi-channel plate, and theplurality of channels comprises a plurality of pores of themulti-channel plate.
 9. The intensified solid-state imaging sensor ofclaim 1 wherein the solid-state image sensor is CCD device.
 10. Theintensified solid-state imaging sensor of claim 1 wherein thesolid-state image sensor is a CMOS device.